In a windows 7 64 bit professional, all ports seems to be blocked/closed, ping included. I shutdown windows firewall and antivirus with no luck. Searching web dosn't help either.
Any ideas on how to approach this (apart of reinstall everything
There could be numerous reasons why the connection is dropping: a flaky connection, driver's are having issue, viruses etc. It'll really be hard to justify the cause, you'll need to approach is in a systematic way and breaking everything down into different layers e.g. physical, datalink, application.
I have had real weird issues in the past and you can't rule out even the most simplest of things like cabling issues or physcial faults. e.g. I've once had a flaky wireless router impacting all other wireless devices. I was getting signals changing from WEP/WPA on one/two laptops, connections were getting dropped to the non-faulty router or some devices weren't able to connect to the working routers. What's unusual was the flaky router seems to functioning quite well but after disabling it, everything just worked again.
More information will be required for us to try help.
Unless there is some kind of firewall you've installed (maybe somewhere between your test node and the target host, instead of on the target host?), this isn't likely worth the trouble to fix. Since this type of problem can also be caused by virus damage from an inserted filter, especially if nothing else in your environment is doing this, you should probably rebuild it.
Sometimes this can happen after security software is removed as well, for similar reasons to it happening after partial virus removal.